282 ROBERT TRACY JACKSON ON ECHINI. 



beyond all reason in splitting. Certainly, without injustice to Girty, his variety of b and his 

 species c and d may reasonably be left under his species b, until better material turns up. 



Delaware Mountain Formation, Carboniferous (Coal Measures), southern Delaware Moun- 

 tains, Texas; and Dark Limestone, Pine Spring, Guadalupe Mountains, Texas. 



Archaeocidaris clavata (Eichwald). 

 Plate 15, fig. 8. 

 Echinocrinus clavatus Eichwald, 1860, p. 653, Plate 23, fig. 16. 



Known only from primary spines, which are club-shaped, above the milled ring expanding 

 to the thickest part, which is near the distal apex, tapering to a blunt end ; with marked, sinu- 

 ous, fluted ridges unlike other known species. 



Carboniferous, Yegorjefsk, in the Province of Kalonga, Russia. 



Lepidocidaris Meek and Worthen. 



Lrpldocidaris Meek and Worthen, 1873, p. 482; Loven, 1874, p. 44; Duncan, 1889a, p. 12; Lanil:)ert and 

 Thie'ry, 1910, p. 126. 



This genus differs very markedlj' from Archaeocidaris, and instead of having many species, 

 as in that genus, there is at present only one species known. The test is high, spheroidal, or 

 perhaps spherical. Ambulacral areas narrow, with two columns of low plates. Ambulacral 

 plates not all alike, but at the mid-zone every third plate is higher and wider than the two inter- 

 mediate and more or less completely abutting against the two smaller plates of the opposite 

 half -area (Plate 17, figs. 2, 3, 12). Interambulacra are wide, with from six to eight columns of 

 large hexagonal plates, or pentagonal in adradial cokmms. The plates are high, rounded, 

 imbricating moderately aborally, and from the center laterally, and over the ambulacrals. 

 Each interambulacral plate has a large perforate primary tubercle with a deep sunken, rather 

 small scrobicular area but no basal terrace. On the high rounded area beyond the scrobicular 

 circle, the surface bears many small secondary tubercles. Spines are long, cylindrical; primary 

 spines are associated with the primary tubercles and minute secondary spines with the secondary 

 tubercles. Oculars and genitals unknown. A typical Palaeozoic inclined lantern exists. 



Type and only known species L. squamosa of the Lower Carboniferous. 



*Lepidocidaris squamosa Meek and Worthen. 

 Plate 16, figs. 1-3; Plate 17, figs. 1-14. 

 Koridaris (?) .iqudiiiosa IMeek and Worthen, 1869, p. 79. 



Eocidaris (?) squamosus Meek and W'orthen, 1873, p. 478, Plate 9, figs. 15a-15g. 

 Lepidocidaris squamosus Meek and Worthen, 1873, p. 478; Jackson, 1896, p. 220, Plate 7, fig. 41; Klein, 



1904, p. 72. 

 Lepidechinus squamosus Keyes, 1895, p. 193. 

 Lepidocidaris squammo?us Lambert and Thiery, 1910, p. 126. 



